/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package javax.servlet.http;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.MessageFormat;
import java.util.Enumeration;
import java.util.ResourceBundle;
import javax.servlet.DispatcherType;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;


/**
 * Provides an abstract class to be subclassed to create an HTTP servlet suitable for a Web site. A
 * subclass of
 * <code>HttpServlet</code> must override at least
 * one method, usually one of these:
 *
 * <ul>
 * <li> <code>doGet</code>, if the servlet supports HTTP GET requests
 * <li> <code>doPost</code>, for HTTP POST requests
 * <li> <code>doPut</code>, for HTTP PUT requests
 * <li> <code>doDelete</code>, for HTTP DELETE requests
 * <li> <code>init</code> and <code>destroy</code>,
 * to manage resources that are held for the life of the servlet
 * <li> <code>getServletInfo</code>, which the servlet uses to
 * provide information about itself
 * </ul>
 *
 * <p>There's almost no reason to override the <code>service</code>
 * method. <code>service</code> handles standard HTTP requests by dispatching them to the handler
 * methods for each HTTP request type (the <code>do</code><i>Method</i> methods listed above).
 *
 * <p>Likewise, there's almost no reason to override the
 * <code>doOptions</code> and <code>doTrace</code> methods.
 *
 * <p>Servlets typically run on multithreaded servers,
 * so be aware that a servlet must handle concurrent requests and be careful to synchronize access
 * to shared resources. Shared resources include in-memory data such as instance or class variables
 * and external objects such as files, database connections, and network connections. See the
 * <a href="http://java.sun.com/Series/Tutorial/java/threads/multithreaded.html">
 * Java Tutorial on Multithreaded Programming</a> for more information on handling multiple threads
 * in a Java program.
 */
public abstract class HttpServlet extends GenericServlet {

    private static final Log log = LogFactory.getLog(HttpServlet.class);

    private static final long serialVersionUID = 1L;

    private static final String METHOD_DELETE = "DELETE";
    private static final String METHOD_HEAD = "HEAD";
    private static final String METHOD_GET = "GET";
    private static final String METHOD_OPTIONS = "OPTIONS";
    private static final String METHOD_POST = "POST";
    private static final String METHOD_PUT = "PUT";
    private static final String METHOD_TRACE = "TRACE";

    private static final String HEADER_IFMODSINCE = "If-Modified-Since";
    private static final String HEADER_LASTMOD = "Last-Modified";

    private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
    private static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);


    /**
     * Does nothing, because this is an abstract class.
     */
    public HttpServlet() {
        // NOOP
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a GET
     * request.
     *
     * <p>Overriding this method to support a GET request also
     * automatically supports an HTTP HEAD request. A HEAD request is a GET request that returns no
     * body in the response, only the request header fields.
     *
     * <p>When overriding this method, read the request data,
     * write the response headers, get the response's writer or output stream object, and finally,
     * write the response data. It's best to include content type and encoding. When using a
     * <code>PrintWriter</code> object to return the response, set the content type before accessing
     * the
     * <code>PrintWriter</code> object.
     *
     * <p>The servlet container must write the headers before
     * committing the response, because in HTTP the headers must be sent before the response body.
     *
     * <p>Where possible, set the Content-Length header (with the
     * {@link javax.servlet.ServletResponse#setContentLength} method), to allow the servlet container
     * to use a persistent connection to return its response to the client, improving performance. The
     * content length is automatically set if the entire response fits inside the response buffer.
     *
     * <p>When using HTTP 1.1 chunked encoding (which means that the response
     * has a Transfer-Encoding header), do not set the Content-Length header.
     *
     * <p>The GET method should be safe, that is, without
     * any side effects for which users are held responsible. For example, most form queries have no
     * side effects. If a client request is intended to change stored data, the request should use
     * some other HTTP method.
     *
     * <p>The GET method should also be idempotent, meaning
     * that it can be safely repeated. Sometimes making a method safe also makes it idempotent. For
     * example, repeating queries is both safe and idempotent, but buying a product online or
     * modifying data is neither safe nor idempotent.
     *
     * <p>If the request is incorrectly formatted, <code>doGet</code>
     * returns an HTTP "Bad Request" message.
     *
     * @param req an {@link HttpServletRequest} object that contains the request the client has made
     * of the servlet
     * @param resp an {@link HttpServletResponse} object that contains the response the servlet sends
     * to the client
     * @throws IOException if an input or output error is detected when the servlet handles the GET
     * request
     * @throws ServletException if the request for the GET could not be handled
     * @see javax.servlet.ServletResponse#setContentType
     */
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_get_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }


    /**
     * Returns the time the <code>HttpServletRequest</code> object was last modified, in milliseconds
     * since midnight January 1, 1970 GMT. If the time is unknown, this method returns a negative
     * number (the default).
     *
     * <p>Servlets that support HTTP GET requests and can quickly determine
     * their last modification time should override this method. This makes browser and proxy caches
     * work more effectively, reducing the load on server and network resources.
     *
     * @param req the <code>HttpServletRequest</code> object that is sent to the servlet
     * @return a <code>long</code> integer specifying the time the <code>HttpServletRequest</code>
     * object was last modified, in milliseconds since midnight, January 1, 1970 GMT, or -1 if the
     * time is not known
     */
    protected long getLastModified(HttpServletRequest req) {
        return -1;
    }


    /**
     * <p>Receives an HTTP HEAD request from the protected
     * <code>service</code> method and handles the
     * request. The client sends a HEAD request when it wants to see only the headers of a response,
     * such as Content-Type or Content-Length. The HTTP HEAD method counts the output bytes in the
     * response to set the Content-Length header accurately.
     *
     * <p>If you override this method, you can avoid computing
     * the response body and just set the response headers directly to improve performance. Make sure
     * that the
     * <code>doHead</code> method you write is both safe
     * and idempotent (that is, protects itself from being called multiple times for one HTTP HEAD
     * request).
     *
     * <p>If the HTTP HEAD request is incorrectly formatted,
     * <code>doHead</code> returns an HTTP "Bad Request"
     * message.
     *
     * @param req the request object that is passed to the servlet
     * @param resp the response object that the servlet uses to return the headers to the client
     * @throws IOException if an input or output error occurs
     * @throws ServletException if the request for the HEAD could not be handled
     */
    protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        if (DispatcherType.INCLUDE.equals(req.getDispatcherType())) {
            doGet(req, resp);
        } else {
            NoBodyResponse response = new NoBodyResponse(resp);
            doGet(req, response);
            response.setContentLength();
        }
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a POST
     * request.
     *
     * The HTTP POST method allows the client to send data of unlimited length to the Web server a
     * single time and is useful when posting information such as credit card numbers.
     *
     * <p>When overriding this method, read the request data,
     * write the response headers, get the response's writer or output stream object, and finally,
     * write the response data. It's best to include content type and encoding. When using a
     * <code>PrintWriter</code> object to return the response, set the
     * content type before accessing the <code>PrintWriter</code> object.
     *
     * <p>The servlet container must write the headers before committing the
     * response, because in HTTP the headers must be sent before the response body.
     *
     * <p>Where possible, set the Content-Length header (with the
     * {@link javax.servlet.ServletResponse#setContentLength} method), to allow the servlet container
     * to use a persistent connection to return its response to the client, improving performance. The
     * content length is automatically set if the entire response fits inside the response buffer.
     *
     * <p>When using HTTP 1.1 chunked encoding (which means that the response
     * has a Transfer-Encoding header), do not set the Content-Length header.
     *
     * <p>This method does not need to be either safe or idempotent.
     * Operations requested through POST can have side effects for which the user can be held
     * accountable, for example, updating stored data or buying items online.
     *
     * <p>If the HTTP POST request is incorrectly formatted,
     * <code>doPost</code> returns an HTTP "Bad Request" message.
     *
     * @param req an {@link HttpServletRequest} object that contains the request the client has made
     * of the servlet
     * @param resp an {@link HttpServletResponse} object that contains the response the servlet sends
     * to the client
     * @throws IOException if an input or output error is detected when the servlet handles the
     * request
     * @throws ServletException if the request for the POST could not be handled
     * @see javax.servlet.ServletOutputStream
     * @see javax.servlet.ServletResponse#setContentType
     */
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_post_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a PUT
     * request.
     *
     * The PUT operation allows a client to place a file on the server and is similar to sending a
     * file by FTP.
     *
     * <p>When overriding this method, leave intact
     * any content headers sent with the request (including Content-Length, Content-Type,
     * Content-Transfer-Encoding, Content-Encoding, Content-Base, Content-Language, Content-Location,
     * Content-MD5, and Content-Range). If your method cannot handle a content header, it must issue
     * an error message (HTTP 501 - Not Implemented) and discard the request. For more information on
     * HTTP 1.1, see RFC 2616
     * <a href="http://www.ietf.org/rfc/rfc2616.txt"></a>.
     *
     * <p>This method does not need to be either safe or idempotent.
     * Operations that <code>doPut</code> performs can have side effects for which the user can be
     * held accountable. When using this method, it may be useful to save a copy of the affected URL
     * in temporary storage.
     *
     * <p>If the HTTP PUT request is incorrectly formatted,
     * <code>doPut</code> returns an HTTP "Bad Request" message.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param resp the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the PUT
     * request
     * @throws ServletException if the request for the PUT cannot be handled
     */
    protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_put_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a
     * DELETE request.
     *
     * The DELETE operation allows a client to remove a document or Web page from the server.
     *
     * <p>This method does not need to be either safe
     * or idempotent. Operations requested through DELETE can have side effects for which users can be
     * held accountable. When using this method, it may be useful to save a copy of the affected URL
     * in temporary storage.
     *
     * <p>If the HTTP DELETE request is incorrectly formatted,
     * <code>doDelete</code> returns an HTTP "Bad Request"
     * message.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param resp the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the DELETE
     * request
     * @throws ServletException if the request for the DELETE cannot be handled
     */
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String protocol = req.getProtocol();
        String msg = lStrings.getString("http.method_delete_not_supported");
        if (protocol.endsWith("1.1")) {
            resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED, msg);
        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
        }
    }


    private static Method[] getAllDeclaredMethods(Class<?> c) {

        if (c.equals(javax.servlet.http.HttpServlet.class)) {
            return null;
        }

        Method[] parentMethods = getAllDeclaredMethods(c.getSuperclass());
        Method[] thisMethods = c.getDeclaredMethods();

        if ((parentMethods != null) && (parentMethods.length > 0)) {
            Method[] allMethods = new Method[parentMethods.length + thisMethods.length];
            System.arraycopy(parentMethods, 0, allMethods, 0, parentMethods.length);
            System.arraycopy(thisMethods, 0, allMethods, parentMethods.length, thisMethods.length);

            thisMethods = allMethods;
        }

        return thisMethods;
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a
     * OPTIONS request.
     *
     * The OPTIONS request determines which HTTP methods the server supports and returns an
     * appropriate header. For example, if a servlet overrides <code>doGet</code>, this method returns
     * the following header:
     *
     * <p><code>Allow: GET, HEAD, TRACE, OPTIONS</code>
     *
     * <p>There's no need to override this method unless the
     * servlet implements new HTTP methods, beyond those implemented by HTTP 1.1.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param resp the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the
     * OPTIONS request
     * @throws ServletException if the request for the OPTIONS cannot be handled
     */
    protected void doOptions(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        Method[] methods = getAllDeclaredMethods(this.getClass());

        boolean ALLOW_GET = false;
        boolean ALLOW_HEAD = false;
        boolean ALLOW_POST = false;
        boolean ALLOW_PUT = false;
        boolean ALLOW_DELETE = false;
        boolean ALLOW_TRACE = true;
        boolean ALLOW_OPTIONS = true;

        // Tomcat specific hack to see if TRACE is allowed
        Class<?> clazz = null;
        try {
            clazz = Class.forName("org.apache.catalina.connector.RequestFacade");
            Method getAllowTrace = clazz.getMethod("getAllowTrace", (Class<?>[]) null);
            ALLOW_TRACE = ((Boolean) getAllowTrace.invoke(req, (Object[]) null)).booleanValue();
        } catch (ClassNotFoundException | NoSuchMethodException | SecurityException | IllegalAccessException
                | IllegalArgumentException | InvocationTargetException e) {
            // Ignore. Not running on Tomcat. TRACE is always allowed.
        }
        // End of Tomcat specific hack

        for (int i = 0; i < methods.length; i++) {
            Method m = methods[i];

            if (m.getName().equals("doGet")) {
                ALLOW_GET = true;
                ALLOW_HEAD = true;
            }
            if (m.getName().equals("doPost")) {
                ALLOW_POST = true;
            }
            if (m.getName().equals("doPut")) {
                ALLOW_PUT = true;
            }
            if (m.getName().equals("doDelete")) {
                ALLOW_DELETE = true;
            }
        }

        String allow = null;
        if (ALLOW_GET) {
            allow = METHOD_GET;
        }
        if (ALLOW_HEAD) {
            if (allow == null) {
                allow = METHOD_HEAD;
            } else {
                allow += ", " + METHOD_HEAD;
            }
        }
        if (ALLOW_POST) {
            if (allow == null) {
                allow = METHOD_POST;
            } else {
                allow += ", " + METHOD_POST;
            }
        }
        if (ALLOW_PUT) {
            if (allow == null) {
                allow = METHOD_PUT;
            } else {
                allow += ", " + METHOD_PUT;
            }
        }
        if (ALLOW_DELETE) {
            if (allow == null) {
                allow = METHOD_DELETE;
            } else {
                allow += ", " + METHOD_DELETE;
            }
        }
        if (ALLOW_TRACE) {
            if (allow == null) {
                allow = METHOD_TRACE;
            } else {
                allow += ", " + METHOD_TRACE;
            }
        }
        if (ALLOW_OPTIONS) {
            if (allow == null) {
                allow = METHOD_OPTIONS;
            } else {
                allow += ", " + METHOD_OPTIONS;
            }
        }

        resp.setHeader("Allow", allow);
    }


    /**
     * Called by the server (via the <code>service</code> method) to allow a servlet to handle a TRACE
     * request.
     *
     * A TRACE returns the headers sent with the TRACE request to the client, so that they can be used
     * in debugging. There's no need to override this method.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param resp the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the TRACE
     * request
     * @throws ServletException if the request for the TRACE cannot be handled
     */
    protected void doTrace(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        int responseLength;

        String CRLF = "\r\n";
        StringBuilder buffer =
                new StringBuilder("TRACE ").append(req.getRequestURI()).append(" ").append(req.getProtocol());

        Enumeration<String> reqHeaderEnum = req.getHeaderNames();

        while (reqHeaderEnum.hasMoreElements()) {
            String headerName = reqHeaderEnum.nextElement();
            buffer.append(CRLF).append(headerName).append(": ").append(req.getHeader(headerName));
        }

        buffer.append(CRLF);

        responseLength = buffer.length();

        resp.setContentType("message/http");
        resp.setContentLength(responseLength);
        ServletOutputStream out = resp.getOutputStream();
        out.print(buffer.toString());
        out.close();
    }


    /**
     * Receives standard HTTP requests from the public
     * <code>service</code> method and dispatches
     * them to the <code>do</code><i>Method</i> methods defined in this class. This method is an
     * HTTP-specific version of the {@link javax.servlet.Servlet#service} method. There's no need to
     * override this method.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param resp the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the HTTP
     * request
     * @throws ServletException if the HTTP request cannot be handled
     * @see javax.servlet.Servlet#service
     */
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        String method = req.getMethod();

        if (method.equals(METHOD_GET)) {
            long lastModified = getLastModified(req);
            if (lastModified == -1) {
                // servlet doesn't support if-modified-since, no reason
                // to go through further expensive logic
                doGet(req, resp);
            } else {
                long ifModifiedSince;
                try {
                    ifModifiedSince = req.getDateHeader(HEADER_IFMODSINCE);
                } catch (IllegalArgumentException iae) {
                    // Invalid date header - proceed as if none was set
                    ifModifiedSince = -1;
                }
                if (ifModifiedSince < (lastModified / 1000 * 1000)) {
                    // If the servlet mod time is later, call doGet()
                    // Round down to the nearest second for a proper compare
                    // A ifModifiedSince of -1 will always be less
                    maybeSetLastModified(resp, lastModified);
                    doGet(req, resp);
                } else {
                    resp.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                }
            }

        } else if (method.equals(METHOD_HEAD)) {
            long lastModified = getLastModified(req);
            maybeSetLastModified(resp, lastModified);
            doHead(req, resp);

        } else if (method.equals(METHOD_POST)) {
            doPost(req, resp);

        } else if (method.equals(METHOD_PUT)) {
            doPut(req, resp);

        } else if (method.equals(METHOD_DELETE)) {
            doDelete(req, resp);

        } else if (method.equals(METHOD_OPTIONS)) {
            doOptions(req, resp);

        } else if (method.equals(METHOD_TRACE)) {
            doTrace(req, resp);

        } else {
            //
            // Note that this means NO servlet supports whatever
            // method was requested, anywhere on this server.
            //

            String errMsg = lStrings.getString("http.method_not_implemented");
            Object[] errArgs = new Object[1];
            errArgs[0] = method;
            errMsg = MessageFormat.format(errMsg, errArgs);

            resp.sendError(HttpServletResponse.SC_NOT_IMPLEMENTED, errMsg);
        }
    }


    /*
     * Sets the Last-Modified entity header field, if it has not
     * already been set and if the value is meaningful.  Called before
     * doGet, to ensure that headers are set before response data is
     * written.  A subclass might have set this header already, so we
     * check.
     */
    private void maybeSetLastModified(HttpServletResponse resp, long lastModified) {
        if (resp.containsHeader(HEADER_LASTMOD)) {
            return;
        }
        if (lastModified >= 0) {
            resp.setDateHeader(HEADER_LASTMOD, lastModified);
        }
    }


    /**
     * Dispatches client requests to the protected
     * <code>service</code> method. There's no need to
     * override this method.
     *
     * @param req the {@link HttpServletRequest} object that contains the request the client made of
     * the servlet
     * @param res the {@link HttpServletResponse} object that contains the response the servlet
     * returns to the client
     * @throws IOException if an input or output error occurs while the servlet is handling the HTTP
     * request
     * @throws ServletException if the HTTP request cannot be handled
     * @see javax.servlet.Servlet#service
     */
    @Override
    public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
        log.info(req);

        HttpServletRequest request;
        HttpServletResponse response;

        try {
            request = (HttpServletRequest) req;
            response = (HttpServletResponse) res;
        } catch (ClassCastException e) {
            throw new ServletException(lStrings.getString("http.non_http"));
        }
        service(request, response);
    }
}


/*
 * A response wrapper for use in (dumb) "HEAD" support.
 * This just swallows that body, counting the bytes in order to set
 * the content length appropriately.  All other methods delegate to the
 * wrapped HTTP Servlet Response object.
 */
// file private
class NoBodyResponse extends HttpServletResponseWrapper {

    private final NoBodyOutputStream noBody;
    private PrintWriter writer;
    private boolean didSetContentLength;

    // file private
    NoBodyResponse(HttpServletResponse r) {
        super(r);
        noBody = new NoBodyOutputStream(this);
    }

    // file private
    void setContentLength() {
        if (!didSetContentLength) {
            if (writer != null) {
                writer.flush();
            }
            super.setContentLength(noBody.getContentLength());
        }
    }

    // SERVLET RESPONSE interface methods

    @Override
    public void setContentLength(int len) {
        super.setContentLength(len);
        didSetContentLength = true;
    }

    @Override
    public void setContentLengthLong(long len) {
        super.setContentLengthLong(len);
        didSetContentLength = true;
    }

    @Override
    public void setHeader(String name, String value) {
        super.setHeader(name, value);
        checkHeader(name);
    }

    @Override
    public void addHeader(String name, String value) {
        super.addHeader(name, value);
        checkHeader(name);
    }

    @Override
    public void setIntHeader(String name, int value) {
        super.setIntHeader(name, value);
        checkHeader(name);
    }

    @Override
    public void addIntHeader(String name, int value) {
        super.addIntHeader(name, value);
        checkHeader(name);
    }

    private void checkHeader(String name) {
        if ("content-length".equalsIgnoreCase(name)) {
            didSetContentLength = true;
        }
    }

    @Override
    public ServletOutputStream getOutputStream() throws IOException {
        return noBody;
    }

    @Override
    public PrintWriter getWriter() throws UnsupportedEncodingException {

        if (writer == null) {
            OutputStreamWriter w;

            w = new OutputStreamWriter(noBody, getCharacterEncoding());
            writer = new PrintWriter(w);
        }
        return writer;
    }
}


/*
 * Servlet output stream that gobbles up all its data.
 */


// file private
class NoBodyOutputStream extends ServletOutputStream {

    private static final String LSTRING_FILE = "javax.servlet.http.LocalStrings";
    private static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);

    private final HttpServletResponse response;
    private boolean flushed = false;
    private int contentLength = 0;

    // file private
    NoBodyOutputStream(HttpServletResponse response) {
        this.response = response;
    }

    // file private
    int getContentLength() {
        return contentLength;
    }

    @Override
    public void write(int b) throws IOException {
        contentLength++;
        checkCommit();
    }

    @Override
    public void write(byte buf[], int offset, int len) throws IOException {
        if (buf == null) {
            throw new NullPointerException(lStrings.getString("err.io.nullArray"));
        }

        if (offset < 0 || len < 0 || offset + len > buf.length) {
            String msg = lStrings.getString("err.io.indexOutOfBounds");
            Object[] msgArgs = new Object[3];
            msgArgs[0] = Integer.valueOf(offset);
            msgArgs[1] = Integer.valueOf(len);
            msgArgs[2] = Integer.valueOf(buf.length);
            msg = MessageFormat.format(msg, msgArgs);
            throw new IndexOutOfBoundsException(msg);
        }

        contentLength += len;
        checkCommit();
    }

    @Override
    public boolean isReady() {
        // TODO SERVLET 3.1
        return false;
    }

    @Override
    public void setWriteListener(javax.servlet.WriteListener listener) {
        // TODO SERVLET 3.1
    }

    private void checkCommit() throws IOException {
        if (!flushed && contentLength > response.getBufferSize()) {
            response.flushBuffer();
            flushed = true;
        }
    }
}
